In some mobile communication systems, a base station can change a radio channel allocated to a mobile station for each frame.
For example, Patent Literature 1 describes (particularly in paragraph 0003) that the base station transmits the uplink MAP message for notifying of the uplink access information (radio channel to be allocated in the uplink frame) and the downlink MAP message for notifying of the downlink access information (radio channel to be allocated in the downlink frame) to the mobile station in every frame so that the common channel can be shared among the respective mobile stations for each frame.